Fix sidebar reducer test

app/soapbox/reducers/__tests__/sidebar-test.js

@@ -2,6 +2,6 @@ import reducer from '../sidebar';
 
 describe('sidebar reducer', () => {
   it('should return the initial state', () => {
-    expect(reducer(undefined, {})).toEqual({});
+    expect(reducer(undefined, {})).toEqual({ sidebarOpen: false });
   });
 });